Enhanced catalyst mobility in chemically amplified resists

Abstract

In chemically amplified resists (CARs), it is known that catalyst diffusion is accelerated by the deprotection reaction. However, the mechanisms that drive this enhancement are not yet known as it is difficult to probe local changes in polymer chemistry and density during the reaction, as well as their effects on catalyst diffusion, through experiments alone. We examine catalyst diffusion in a model terpolymer CAR, both in the presence and absence of reaction, using a combination of experiments and atomistic simulations. From experiments, we find that deprotection rates are faster than film densification, and that reaction enhances long-time catalyst diffusion lengths by a factor of four. From simulations, we find evidence that catalyst mobility is enhanced in recently reacted regions of the terpolymer. These results provide insight into the origins of accelerated catalyst diffusion during reaction, and will be utilized in the development of physics-informed models of CAR systems.